Analyzing USB
How do people use an oscilloscope to analyze USB packets and such? I saw a video by Ben Eater and the way he did it was by exposing the necessary wires of a USB cable and probing those. Is this standard or are there types out there that have this functionally built-in as some accessory or something?
Edit: logic analyzers are pretty interesting
13 replies
FYI you can also just use wireshark
Wireshark can do USB protocol analysis?????
Depends on how low level you need. If you're just looking at the data being sent, then Wireshark will work fine; I've even used it to help reverse engineer a UPS. If you're investigating interference/timing/collisions/whatever then you'd need a scope or logic analyser.
Deleted - Replied to wrong comment.
You would be looking for a scope with a logic analyzer function.
Was it a logic analyzer instead, like https://www.saleae.com/logic?
Checked the video again. He used a Keysight DSOX1204G Digital Storage Oscilloscope.
https://www.youtube.com/watch?v=wdgULBpRoXk
I have the same scope, but it doesn’t have USB decode. I watched the video and he’s initially doing the decoding very manually. Fun, but not something you’re going to want to do when someone’s paying for your time.
He later switches to a Keysight DSO-X 4024A. It costs a fair bit more. :)
Been doing some digging now knowing about logic analyzers and I found that RIGOL has some oscilloscopes with digital channels that are within my budget range (needs the RPL1116 probe to function). Though they're bandwidth is 100MHz for the one's I could find that are under 500-1,000$. Would this be enough at least for USB 2.0?
Does it have built-in USB decoding? If not then it’s not very practical tbh, but it could do low speed and full speed, with manual decoding. Not high speed.
OpenVizsla can do high speed: https://shop.sysmocom.de/USB-Tracing/
What are you after though? A scope is more fun. :)
I'm trying to learn electrical circuit design and programming and want/need an oscilloscope for obvious reasons (I already have most of the basic stuff such as a soldering station and a multimeter). I know I want to work with various ICs, FPGAs, and of course stuff like USB to plug stuff. Though budget isn't that extravagant, I should have decent wiggle room (I suppose totals of below or around 700$ is fairly manageable at the moment).
That sounds like an expensive oscilloscope.
I use an OpenVizsla.
The one Ben Eater was using was a Keysight 200MHz, I think with 2GS/s sampling.